Rotary fluid motor

ABSTRACT

This fluid motor has three interengaging identical rotors. Each rotor has a configured periphery providing a series of peripheral projections and recesses in the pattern of a serially repeated succession of identically spaced series of piston blade, gear recess, gear tooth, and piston-blade-receiving notch. An highpressure inlet port goes into a space between the first and second rotors, and a medium-pressure output is connected from each of the chambers of the first and second rotors to another inlet port between the second and third rotors. There are lowpressure outlet ports from each of the rotors-these ports also being connected together.

mted States Patent .11 1 1111 3,846,987

Baldwin Nov. 12, 1974 [5 ROTARY FLUID MOTOR Primary Examiner-William L. F reeh Assistant Examiner-O. T. Sessions B Id 2 l [76] Inventor e Way Attorney, Agent, or FirmOwen, Wrckersham &

Erlckson [22] Filed: Oct. 16, 1973 [21] Appl. No.: 406,947 [57] ABSTRACT This fluid motor has three interengaging identical rol Cl 6 /690, 418/10, 4l8/l96, tors. Each rotor has a configured periphery providing 418/205 .1 series of peripheral projections and recesses in the [51] int. Cl Folk 7/02 pattern of a serially repeated succession of identically [53] Field O Search spaced series of piston blade, gear recess, gear tooth, 60/690 7 and piston-blade-receiving notch. An high-pressure inlet port goes into a space between the first and sec- [56] References Cited 0nd rotors, and a medium-pressure output is con- UNITED STATES PATENTS nected from each of the chambers of the first and sec- 149 664 4/1974 La France 418/205 0nd rotors to another inlet Port between the Second 664:765 12 1900 Legendre 418/10 and third rotors- There are low-Pressure Outlet Ports 768,320 8/1904 White 60/690 f each of the rotors-these p ts also being con- 878,6l3 9/1907 Dibbell 418/10 nected together. I 1,207,306 lZ/l9l6 Lestak 4l8/l5 9 Claims, 5 Drawing Figures 3.846.987 SHEEI 10$ 2 PATENTEUHBV 12 I974 '1 ROTARY FLUID MOTOR BACKGROUND OF THE INVENTION gines heretofore in use. These problems are so well known that they need not be detailed here. They are serious enough to lead many to conjecture that internal combustion engines may not be tolerable muchlonger, even for automobiles, buses, and trucks. Therefore, many attempts are being made to seek other ways of powering such vehicles and of providing engines that would produce less pollution.

An object of the present invention is to provide a fluid motor which can serve as part of a vehicle engine or can also be used in a stationary engine. Another object is to provide an engine which is relatively nonpolluting and is very low in noise and vibration. The heart of the device of this invention is a novel fluid motor, but there are also aspects concerning the connection of that motor to an external type of combustion device in which fuel may be burned efficiently and substantially non-pollutingly, at least so far as the most objectionable pollutants are concerned.

SUMMARY OF THE INVENTION The fluid motor of the invention comprises a hollow casing in which are three interengaging cylindrical rotors that rotate in three respective chambers. The rotors are preferably identical and have a novel shape: the periphery of each is made up of a series of peripheral projections and recesses providing for the interengagement of each rotor with'another. A' succession of serially repeated identically spaced series of piston blade, gear recess, gear tooth and piston-bladereceiving notchis provided. The rotors rotate together, with a second or central rotor rotating in the opposite direction from the first and third rotors, whichdo not engage with each other. Each blade of each rotor engages a notch of another rotor and vice versa during each revolution and similarly each gear tooth of each rotor engages'a gear recess of another rotor andvice versa during each revolution.'

Each of the piston-bladereceiving notches comprises two cyclindrical concave arcs meeting at a vertex. One arc defines one edge of its adjacent piston blade and the other are defines one edge of its adjacent gear tooth. Each gear recess is partially defined by another edge of the adjacent gear tooth and by a second edge of the adjacent piston blade. The second edge of the blade is a cylindrical convex are, which, during engagement with the notch of the adjacent rotor, is in .sliding contact therewith.

The casing provides two inlet ports: a first highpressure inlet port is located at an upper intersection of the first and second chambers and is offset upwardly from the plane joining the parallel axes of the first and I second rotors; the second inlet port is at the lower intersection of the second and third chambers and is offset downwardly from the plane joining the axes of the second and third rotors, so that it lies on the opposite side from the first inlet port. Preferably, the three axes lie in a single plane. The casing also has a pair of medium-pressure outlet ports, respectively, from the first and second chambers, at a suitable rotational distance beyond the first inlet port. Suitable conduits connect these two outlet ports for medium-pressure gas to the second inlet port. The casing also has six additional outlet ports which are joined together in an outlet conduit, one from each of the first and third chambers and four from the second chamber, allproviding outlet gas at a lower pressure from that in the medium-pressure outlet ports.

'In the use of the device as an engine, the fluid motor is combined with an exterior arrangement which includes a burner for burning fuel mixed with air in an efficient and substantially non-polluting manner, and the hot combustion product passes through a heat exchanger causing a liquid coming from a storage tank to be vaporized and thensend the gas therefrom to the first inlet port of the fluid motor. The low-pressureoutlet gas is then returned from the motor to a condenser, where it is liquefied for recirculation to the heat exchanger.

Other objects and advantages of the invention will appear from the following detailed description of a preferred embodiment, .it being understood that many other embodiments could be made within the spirit and scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a view in elevation of a fluid motor embodying the principles of the invention, with the front casing cover plate removed. 7

FIG. 2 is a plan view of the complete motor of FIG. 1, with some portions broken away and shown in section.

FIG. 3 is a view in front elevation of the motor of FIG. 1, with the front cover plate in place.

FIG. 4 is a diagrammatic view of the portions of the engine exterior to the fluid motor.

FIG. 5 is a fragmentary enlarged view in section taken along the line.5 5 in FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT is hollow and provides an interior portion essentially comprising three interfering or'intersecting cylinders 17, 18, and 19. I

Inside the three cylinders 17, 18, and 19 are respectively first, second, and third interengaging rotors 21, 22, and 23. These rotors 21, 22, and 23 are cylindrical in shape, each of them having flat wall portions facing the flat walls of the cover plates 13 and 14. The rotors 21, 22, and 23 are, respectively, secured to threeshafts 24, 25, and 26, any or all of which may be used as power output shafts, but preferably only the center shaft 25 is so used. The three rotors 21, 22, and 23 are thereof from an outer portion 29 having an unusually shaped outer peripheryv Each rotor periphery comprises a succession of serially repeated identically spaced series of four members, namely, a piston blade 30, a gear recess 31, a gear tooth 32, and a piston-blade-receiving notch 33. The piston blade 30 is defined on one side by a concave cylindrical are 34, which also is one surface of the preceding notch 33. The other surface of the piston blade 30 is a convex cylindrical are 35, which leads into the succeeding gear tooth recess 31. The gear tooth recess 31 leads directly to the gear tooth 32'and shares a surface in-common with that, and one side of the gear tooth 32 is made up of a second concave are 36 of the succeeding bladereceiving notch 33. The arcs 35 and 36 are preferably part of the same circle, and on the are 35 is the tip 37 of each piston blade 30. The gear teeth 32 have tips 38, and the gear recesses 31 have bases 39.

The three shafts 24, 25, and 26 are located along parallel axes 41, 42, and 43, respectively, which are located so that the rotors 21, 22, and 23 are properly interengaged. A theoretical circle 40 having a radius equal to half the distance between the axes 41 and 42 (and therefore equal to half the distance between the axes 42 and 43), is used in arriving at the configuration of the rotor periphery. The centers of the arcs 35 and 36 (which are parts of the same circle) lie on the circumference of the circle 40, and they are located at the intersection therewith of the radial line from the axis 41, 42, or 43 to the point where the are 35 meets the circle described by the tip 37, i.e., the end of the tip 37. The arcs 35 end at the circle 40, and the gear recess 31 is from there defined by straight sloping lines 45 and 46. The gear tooth 32 is defined outside the circle 40 by sloping lines 47 and 48 that extend from the circle 40 to a desired gear tip width that enables the gear tooth 32 to wipe the recess 31. The are 36 goes in from the circle 40 to its intersection with the are 34 at a short distance beyond the radial line 44. The arc 34 is centered on the circle 40 where the center 40 meets the are 34 and the sloping line 48.

While the size, the spacing, and the number of the serially repeated series may vary, it may be helpful to give some examples of sizes, shapes, etc. For example, the diameter "of each of the rotors 21, 22, 23 may be 12 inches, although it could be larger or smaller, and the thickness of each rotor 21, 22, 23 may conveniently lie between 2 and 6 inches, although it could be somewhat larger or somewhat smaller. Supposing that 12-inchdiameter rotors 21, 22,'and 23 are to be used, they may be placed on parallel axes 41, 42, and 43 inches apart and these three axes 41, 42, and 43 preferably lie in one horizontal plane 49. A l2-inch-diameter rotor may have 10 piston blades 30 and therefore 10 notches 33, 10 gear teeth 32, and 10 gear recesses 31. If one were to construct a circle 40 with a radius of 5 inches about each axis 41, 42, and 43, the piston blades would lie about 3-1/7 inches apart on that 5-inch-radius circle 40. The radius of the concave are 34 would then be 1-7/16 inches centered on the circle 40, and the edge of the are 34 would meet the notch curve 36 at one-eighth inch past the radial line 44 running from the piston tip 37 to the rotor axis. Both of the notch arcs 34- and 36 have centers on the circumference of this circle 40 and, in this example, would meet one-eighth inch past the radial line 44. The arcs and 36 would have a l-inch radius, centered where the circle intersects the radial line 44; they are parts of the same circle. The bottom of each gear recess 31 may be threeeighths of an inch wide in this particular example, with the lines 45 and 46 sloping accordingly from the circle 40, and the gear teeth 32 would then be one-fourth inch thick at their tips 38, with the lines 47 and 48 sloping accordingly from the circle 40. The piston blades 30, the gear teeth 32, and the gear notches 31 could each be nine-sixteenths inch wide or thick on the circumference of the 5-inch-radius circle 40. The gear teeth 32 and the gear recess 31 extend one-half inch each side of the circle 40. These, of course, are only examples, but they will give some idea of what is involved.

It will be clear then, from the drawings, thatthe gear teeth 32 enter and leave the gear recess 31 and help to provide the continuity of action, asdo the blades 30 andnotches 33, which provide the principal gas compression and expansion, though the gear teeth 37 and recesses 31 also performsome compression and expansion. The motor 10 is powered by gas under pressure produced in a manner such as will be described later, or by another means, if desired. The gas enters initially at high pressure a first inlet port 50 between the upper halves of the first and second rotors 21 and 22. The notches 33 are wiped by the blades 30 to provide a sealing contact edge, and, at this portion of the device, the tips 37 of the blades 30 are also in contact with the side wall enclosure 11. The gas pressure in the resulting chambers causes the first and second rotors 21 and 22 to revolve in opposite directions.

Outlet openings 51 and 52 are provided a suitable rotational distance beyond the first high-pressure inlet opening 50, and always within the first 90 thereof. These outlet ports 51 and 52 lead gas at medium pressure respectively by conduits 53 and 54, one from the first chamber 17 and one from the second chamber 18. These conduits 53 and 54 may profitably be joined together and at least are joined in common to a second inlet port 55, which lies between the second and third rotors 22 and 23 below the horizontal plane 49, on the opposite side from the first inlet port 50 and otherwise at about the same location. Low pressure outlet openings or ports 56, 57, 58, and 59 are provided in each of the three chambers 17, 18, and 19, there being two such outlet openings 57 and 58- from the second chamber 18: one port 57 lying rotationally between the medium pressure outlet 52 thereof and the second inlet 55 and the other lying beyond the second inlet port 55. The ports 56 and 57 lie far enough beyond the ports 51 and 52 so that they are always separated therefrom by at least one blade 30. The gas from these four outlet ports is preferably collected into a common conduit 60 for condensation, as will be explained later.

During the portions of the cycles described so far, the blades 30 wipe the enclosure 11 along an are 61 in the chamber 17, the full cylindrical periphery 62 of the chamber 18, and an are 63 in the chamber 19. Beyond the port 56, the chamber 17 is recessed outwardly along an are 64 which is out ofcontact with the blades 30, and beyond the port 59, the chamber 19 is recessed outwardly along an are 65 which is out of contact with the blades 30. To prevent pressure from bleeding back into these areas from the conduit 60, check valves 66 and 67 are provided, respectively, between the ports 56 and 59 and any other ports opening into the conduit 60. The recessed arcs 64 and 65 reduce wear on the tips 37 the cover plates 13 and 14 may be recessed away from rotor contact. The arcs 64 and 65 end and the arcs 61- and 63 begin as the blades 30 approach interengagement with the rotor 22.

Oil wipes 68 are preferably provided at the locations shown in the drawing, wherethe blades 30 are approaching the intersections, to enable lubrication between the rotors 21, 22, 23 and the casinglO. These may be provided by recesses in the enclosure wall .12 and in the side plates 13 and 14, the recesses being filled with felt, which is fed with oil under substantially constant pressure. The piston blades 30 and gears 32 preferably have rounded edges so that they do not sweep the oil film from the enclosure 12, and the surfaces of the cover plates 13 and 14. The grooves 28 in the rotors retain sealing rings 69 in order to prevent propellant and lubricant leakage.

The outer working portions 29 of the rotors 21, 22,

and 23 are the same thickness as the enclosure wall 12, i.e., the thickness of the chambers 17, 18, and 19, or substantially so, with lubrication therebetween but with a gentle contact. The central or inner portions 27 of the rotors 21, 22, and 23 may be much less thick, since the sealing rings 69 relieve them of the necessity of making contact. For example, the portions 27 may be threefourths of an inch or less in thickness, or may be thicker if desired.

A series of caps 70 may be provided for retaining lubricant for the axle bearings 24a, 25a, and 26a and to protect those bearings from dirt. These caps 70 may be on all the axlebearings except the outgoing power shaft 25. Y

When the rotors 21 and 22 (or 22 and 23)'begin to come together, it is important to prevent in-pressure from building up prior to the inlet ports 50 and 55.

Therefore, additional ports 71 and 72 lead into the outlet conduit 60 from the chamber 18.

A conduit 75 leads to the first inlet 50, and the conduit 75 is provided with a valve 76 of-thebutterfly type for regulating the incoming propellant'gas. This valve 76 may be foot-controlled in a vehicle, for example, and enables the operatorto cause the rotors 21, 22, and 23 to revolve either fast or slow, or to stop. A footcontrol shutoff butterfly valve 77 may also be located in the gas return pipe 60 leading from the low-pressure outlet ports 56, 57, 58, 59, 71, and 72 to a condenser as shown in FIG. 4. When this valve 77 is closed and the power control valve 76 is also closed, a braking action results which is very beneficial when the device is used in vehicles on downhill grades.

It may be desirable to have the gas from the conduit 75 enter the inlet port 50 at an angle, rather than entering perpendicular to the cover plates 13 and 14. This may be done by having an inlet conduit 75 that leads in to the conduit 50 at an angle of, say, 45 or byhaving deflector plates to deflect the passage of gas to the 45 position or some similar position. Flatter or sharper angles may be employed if desired.

To prevent the side plates 13 and 14 from bulging due to pressure, a series of external I-beams 78 may be used and may be secured to the cover plates 13 and 14 by suitable studs 79. Studs 79 and 15 are used throughout, so that one cover plate 13 may be removed from the enclosure 12 without disturbing the other side plate 14.

A very important part. of this invention is that the piston blades 30 on each rotor 21, 22, 23 cooperate with the notches 33 on the adjacent rotor to-provide a constant and continual push of power. Another feature is the secondary use of part of the pressurized gas by. the

combination of the third rotor 23 with the other two.-

The third rotor 23 should enable the addition of up to 40 percent additional power with the same amount of fuel and expended gas returning to the condenser, and

this gas is lessdifficult to return to its liquid state.

. This fluid motor 10 is in itself non-polluting, substantially vibrationless and practically noiseless. it starts smoothly and does not require any clutch or ignition system internally nor does it require any inlet or outlet valves-the ports being quite sufficient. As has already been pointed out, it is self-braking on down grades.

The fluid motor 10 may be combined with various types of supply and exhaust systems. It will work, for example, on application of compressed air which could beexhausted to the atmosphere quite safely and may be therefore powered by any suitable compressing means. However, FIG. 4 shows one system in which the device could be used that will'make clearer how it will be used in connection withan external combustion system.

FIG. 4 shows a fuel jet 80 leading from a fuel pipe 81 into a burner 82. Warm air from a radiator fan 83 may be used to help provide improvedcombustion, and the combustion products lead into a heat exchanger 84. The input tothe heat exchanger 84 comes via a liquid pump 85 from a liquid storage device 86 or directly from a condenser 87, which is connectedto the liquid storage device 86 and which includes a radiator 88, where the air is warmed while cooling the gases returning from the engine. The hot gases may be let into a storagetank 89 to enable their use as desired at varying power requirements, or if desired, may lead directly to the engine. Preferably, there is a fuel jet 90 and a'liquid pump controlgauge 91 on the storage tank 89. The combustion products exhausted to atmosphere consist essentially of carbon dioxide and water and do not have the fouling type of pollutants produced from incomplete combustion or from high compression engines and catalytic reactions. Obviously, leaded fuel has no advantage here, and in fact, the fuel can be substan' tially any type of fuel desired. The high-pressure gas goes to the first inlet port 50 of thefiuid-handling device 10 to operate it and then is returned from its lowpressure outlet ports by the conduit v60 to the radiator 88 and condenser 87.

To those skilled in the art to which this invention relates, many changes in construction and widely differsuggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. A rotary fluid motor including in combination;

a hollow casing providing an interior, chamber shaped substantially as first, second, and third successive and intersecting cylindrical chambers with flat side walls,

first, second, and third identical, interengaging genverally cylindrical rotors, each in and aligned with the respective said cylinder, said rotors having lateral flat surfaces facing said side walls and being mounted in said casing for rotation about three-respective spaced-apart, parallel, axes,

each said rotor having its periphery consisting of a series of peripheral projections and recesses providing for the interengagement of said rotors and comprising a serially repeated succession of identically spaced series of piston blade, gear recess, gear tooth, and piston-blade-receiving notch, whereby said rotors rotate together with said second rotor rotating in the opposite direction from said first and third rotors, with each blade of each rotor engaging a notch of another rotor, and vice versa, during each revolution, and each gear tooth of each rotor engaging a gearrecess of another rotor, and vice versa, during each revolution, to provide said interengagement and to synchronize the rotary movement of said rotors,

each said notch comprising two cylindrical concave arcs meeting at a vertex, one said are defining one edge of a blade, the other said are defining one edge of a said gear tooth, each said gear recess being partially defined by another edge of its adjacent said gear tooth and by a second edge of its adjacent said blade, said second edge being a cylindrical convex are which during engagement with the notch of its adjacent rotor is in sliding contact therewith, said casing having a first inlet port at the intersection of said first and second chambers offset from the plane joining the axes of said first and second rotors, a second inlet port at the intersection of said second and third chambers offset from the plane joining the axes of said second and third rotors and on the opposite side from said first inlet port, said casing having first and second outletports from said first and second chambers respectively,-.each at a rotational distance less than 90 beyond said first inlet port, first conduit means connecting said first and second outlet ports to said second inlet port, said casing having a third outlet port lying rotationally beyond said first outlet port from said first chamber, and at all times separated therefrom by at least one said blade, a fourth outlet port from said second chamber rotationally between said second outlet port and said second inlet port, and at all times separated therefrom by at least one said blade, a fifth outlet port from said second chamber rotationally beyond said second inlet port, and a sixth outlet port from said third chamber rotationally beyond said second inlet port, and second conduit means for outlet gases connected to said third, fourth, fifth, and sixth outlet ports. 2. The fluid motor of claim 1 wherein said first and third chambers each have outwardly offset arcuate cylindrical surfaces beyond, respectively, said third and sixth outlets, where the tip of said blade does not engage for a substantial arcuate distance.

3. The fluid motor of claim 2 wherein said second conduit means has check valve means for said third and sixth outlet ports.

4. The fluid motor of claim 1 having seventh and 6S eighth outlet ports opening into said second conduit means from a location just prior to interengagement of said rotors.

5. The fluid motor of claim 1 having a shaft for each said rotor, the second said rotor having its shaft extend outside said casing as a power output shaft.

6. The fluid motor of claim 1 wherein the centers of the arcs of said blade and notch lieon a theoretical circle whose center is the axis of the rotor and whose radius is half the distance between adjacent axes, said convex arc and the are common to said notch and said gear tooth being arcs of the same circle and centered on the intersection of said theoretical circle and a radial line from said axis to the tip of said blade.

7. The fluid motor of claim 1 having butterfly type valves in said first conduit and in said second conduit, enabling acceleration, deceleration, and braking action by said motor.

8. The fluid motor of claim 1 wherein said casing comprises a hollow side wall enclosure and a pair of flat cover plates closing said enclosure and having in them said ports.

9. An engine, including in combination:

combustion means for burning a fuel air mixture,

heat-exchange means connected to said combustion means,

a source of vaporizable liquid connected to said heat exchange means and in heat-exchange relation with the burned fuel air mixture, so as to vaporize said liquid,

a gas storage tank for vaporized liquid from said heat exchanger,

a rotary fluid motor having a hollow casing providing an interior chamber shaped substantially as first, second, and third successive and intersecting cylindrical chambers with flat side walls, first, second, and third identical, interengaging generally cylindrical rotors, each in and aligned with the respective said cylinder, said rotors having lateral flat sur faces facing said side walls and being mounted in said casing for rotation about three respective spaced-apart, parallel, axes,

each said rotor having its periphery consisting of a series of peripheral projections and recesses providing for the interengagement of said rotors and comprising a serially repeated succession of identically spaced series of piston blade, gear recess, gear tooth, and piston-blade-receiving notch, whereby said rotors rotate together with said second rotor rotating in the opposite direction from said first and third rotors, with each blade of each rotor engaging a notch of another rotor, and vice versa, during each revolution, and each gear tooth of each rotor engaging a gear recess of another rotor, and vice versa, during each revolution, to provide said interengagement and to synchronize the rotary movement of said rotors,

each said notch comprising two cylindrical concave arcs meeting at a vertex, one said are defining one edge of a blade, the other said are defining one edge of a said gear tooth, each said gear recess being partially defined by another edge of its adjacent said gear tooth and by a second edge of its adjacent said blade, said second edge being a cylindrical convex arc which during engagement with the notch of its adjacent rotor is in sliding contact therewith, said casing having a first inlet port at the intersection of said first and second chambers offset from the plane joining the axes of said first and second rotors, said first inlet port being connected to said gas storage tank, a second inlet port at the intersection of said second and third chambers offset from the plane joining the axes of said second and third rotors and on the opposite side from said first inlet port,

said casing having first and second outlet ports from said first and second chambers respectively, each at a rotational distance less than 90 beyond said first inlet port,

first conduit means connecting said first and second outlet ports to said second inlet port, v 7

said casing having a third outlet port lying rotationally beyond said first outlet port from said first chamber, a fourth outlet port from said second chamber rotationally between said second outlet port and said second inlet port, a fifth outlet port from said second chamber rotationally beyond said second inlet port, and a sixth outlet port from said third chamber rotationally beyond said second inlet port,

second conduit means connecting together said third,

fourth, fifth, and sixth outlet ports, and

a condenser connected to said second conduit means and to said source of vaporizable liquid, for condensing the gas from said motor and returning it to said source in liquid form. 

1. A rotary fluid motor including in combination: a hollow casing providing an interior chamber shaped substantially as first, second, and third successive and intersecting cylindrical chambers with flat side walls, first, second, and third identical, interengaging generally cylindrical rotors, each in and aligned with the respective said cylinder, said rotors having lateral flat surfaces facing said side walls and being mounted in said casing for rotation about three respective spaced-apart, parallel, axes, each said rotor having its periphery consisting of a series of peripheral projections and recesses providing for the interengagement of said rotors and comprising a serially repeated succession of identically spaced series of piston blade, gear recess, gear tooth, and piston-blade-receiving notch, whereby said rotors rotate together with said second rotor rotating in the opposite direction from said first and third rotors, with each blade of each rotor engaging a notch of another rotor, and vice versa, during each revolution, and each gear tooth of each rotor engaging a gear recess of another rotor, and vice versa, during each revolution, to provide said interengagement and to synchronize the rotary movement of said rotors, each said notch comprising two cylindrical concave arcs meeting at a vertex, one said arc defining one edge of a blade, the other said arc defining one edge of a said gear tooth, each said gear recess being partially defined by another edge of its adjacent said gear tooth and by a second edge of its adjacent said blade, said second edge being a cylindrical convex arc which during engagement with the notch of its adjacent rotor is in sliding contact therewith, said casing having a first inlet port at the intersection of said first and second chambers offset from the plane joining the axes of said first and second rotors, a second inlet port at the intersection of said second and third chambers offset from the plane joining the axes of said second and third rotors and on the opposite side from said first inlet port, said casing having first and second outlet ports from said first and second chambers respectively, each at a rotational distance less than 90* beyond said first inlet port, first conduit means connecting said first and second outlet ports to said second inlet port, said casing having a third outlet port lying rotationally beyond said first outlet port from said first chamber, and at all times separated therefrom by at least one said blade, a fourth outlet port from said second chamber rotationally between said second outlet port and said second inlet port, and at all times separated therefrom by at least one said blade, a fifth outlet port from said second chamber rotationally beyond said second inlet port, and a sixth outlet port from said third chamber rotationally beyond said second inlet port, and second conduit means for outlet gases connected to said third, fourth, fifth, and sixth outlet ports.
 2. The fluid motor of claim 1 wherein said first and third chambers each have outwardly offset arcuate cylindrical surfaces beyond, respectively, said third and sixth outlets, where the tip of said blade does not engage for a substantial arcuate distance.
 3. The fluid motor of claim 2 wherein said second conduit means has check valve means for said third and sixth outlet ports.
 4. The fluid motor of claim 1 having seventh and eighth outlet ports opening into said second conduit means from a location just prior to interengagement of said rotors.
 5. The fluid motor of claim 1 having a shaft for each said rotor, the second said rotor having its shaft extend outside said casing as a power output shaft.
 6. The fluid motor of claim 1 wherein the centers of the arcs of said blade and notch lie on a theoretical circle whose center is the axis of the rotor and whose radius is half the distance between adjacent axes, said convex arc and the arc common to said notch and said gear tooth being arcs of the same circle and centered on the intersection of said theoretical circle and a radial line from said axis to the tip of said blade.
 7. The fluid motor of claim 1 having butterfly type valves in said first conduit and in said second conduit, enabling acceleration, deceleration, and braking action by said motor.
 8. The fluid motor of claim 1 wherein said casing comprises a hollow side wall enclosure and a pair of flat cover plates closing said enclosure and having in them said ports.
 9. An engine, including in combination: combustion means for burning a fuel air mixture, heat-exchange means connected to said combustion means, a source of vaporizable liquid connected to said heat exchange means and in heat-exchange relation with the burned fuel air mixture, so as to vaporize said liquid, a gas storage tank for vaporized liquid from said heat exchanger, a rotary fluid motor having a hollow casing providing an interior chamber shaped substantially as first, second, and third successive and intersecting cylindrical chambers with flat side walls, first, second, and third identical, interengaging generally cylindrical rotors, each in and aligned with the respective said cylinder, said rotors having lateral flat surfaces facing said side walls and being mounted in said casing for rotation about three respective spaced-apart, parallel, axes, each said rotor having its periphery consisting of a series of peripheral projections and recesses providing for the interengagement of said rotors and comprising a serially repeated succession of identically spaced series of piston blade, gear recess, gear tooth, and piston-blade-receiving notch, whereby said rotors rotate together with said second rotor rotating in the opposite direction from said first and third rotors, with each blade of each rotor engaging a notch of another rotor, and vice versa, during each revolution, and each gear tooth of each rotor engaging a gear recess of another rotor, and vice versa, during each revolution, to provide said interengagement and to synchronize the rotary movement of said rotors, each said notch comprising two cylindrical concave arcs meeting at a vertex, one said arc defining one edge of a blade, the other said arc defining one edge of a said gear tooth, each said gear recess being partially defined by another edge of its adjacent said gear tooth and by a second edge of its adjacent said blade, said second edge being a cylindrical convex arc which during engagement with the notch of its adjacent rotor is in sliding contact therewith, said casing having a first inlet poRt at the intersection of said first and second chambers offset from the plane joining the axes of said first and second rotors, said first inlet port being connected to said gas storage tank, a second inlet port at the intersection of said second and third chambers offset from the plane joining the axes of said second and third rotors and on the opposite side from said first inlet port, said casing having first and second outlet ports from said first and second chambers respectively, each at a rotational distance less than 90* beyond said first inlet port, first conduit means connecting said first and second outlet ports to said second inlet port, said casing having a third outlet port lying rotationally beyond said first outlet port from said first chamber, a fourth outlet port from said second chamber rotationally between said second outlet port and said second inlet port, a fifth outlet port from said second chamber rotationally beyond said second inlet port, and a sixth outlet port from said third chamber rotationally beyond said second inlet port, second conduit means connecting together said third, fourth, fifth, and sixth outlet ports, and a condenser connected to said second conduit means and to said source of vaporizable liquid, for condensing the gas from said motor and returning it to said source in liquid form. 